Applying a camouflage material to multiple objects without merging them
In the link above, the answer refers to using 'Object' texture coordinates.  If you use Object coordinates on multiple objects, you'll still have the same issue you currently have:



However, the power of Object coordinates is that you can use any object, and you can use the same object for everything that uses the same material:



In this example I modeled a cube that I called "Texture_Cube" and I use that in the Object field of the "Texture Coordinate" node.  You can see all of the objects now have the same texture coordinates:

   

Here's the full node graph:



You don't have to use a giant cube like I did; you can use anything, even an Empty. You can also do fun stuff like rotate the object and it'll rotate your textures.  Hope this helps!